A previous commentor is incorrect; there is no problem with Direct3D 7 (which is what he really means) on nVidia cards, and in any case the video card drivers have nothing to do with DirectX, per se, beyond exposing the features required to be present for DirectX certification at a specific interface version.
Also, later DirectX versions by definition will present earlier interfaces and only offer the interface they are queried for (in other words, older software sees the version it was written for and cannot usually use newer features it doesn't know about but it will have no problems with the version it wants), Direct3D 7 was very widely used and I still run a lot of software that expects it rather than 8, 8.1 or 9 (I use XP 64, so no 10 or 10.1). For reference, my nVidia card is a GeForce GTX 295 and I'm using the very latest WHQL drivers - 6.14.0011.9562 (AKA 195.62) with absolutely no problems at all, I ran DXDiag just to be sure. :¬)
I hope this helps anyone who might have been put off by the possibility of not being able to run this on their shiny new toys.
P.S. I have rated it a 5 to shift the average up and because a rating is required and the game does sound interesting but I have not actually played this game.